For whatever reason, ru->frame_parms was NULL and the RRU crashed.
Let's allocated memory.
Also, don't do fp = ru->frame_parms in ru_thread, it seems that it
takes the value before allocation (so: NULL) and the code crashes
later on.
Maybe it's not the correct solution. To be refined at some point.
end_of_burst_delay is used to stop TX only "after a while".
If we stop right after effective signal, with USRP B210 and
B200mini, we observe a high EVM on the S subframe (on the
PSS).
A value of 400 (for 30.72MHz) solves this issue. This is
the default.
This default value can be changed in the configuration file.
For example:
RUs = (
{
local_rf = "yes"
nb_tx = 1
nb_rx = 1
att_tx = 20
att_rx = 0;
bands = [7];
max_pdschReferenceSignalPower = -27;
max_rxgain = 105;
eNB_instances = [0];
sf_extension = 312;
end_of_burst_delay = 200;
}
);
Here we would set a value of 200.
The value to put in the configuration file is for
30.72MHz. The value is scaled accordingly at runtime
(thus only one value to set for every RB configuration,
25, 50 or 100, leading to less problems when adapting
configuration files).
This option is for experts and should not be changed
randomly.
Start of burst is to start TDD DL transmission in the driver
(tested with USRP for the moment).
End of burst is to stop DL transmission.
Start of burst can only happen for a DL subframe when the
previous subframe was an UL subframe.
End of burst can only happen for an S subframe.
It's impossible for a subframe to be both the start of a burst
and the end of a burst.
This can be checked with eg. http://niviuk.free.fr/lte_resource_grid.html
(or reading the specs).
This parameter is meaningful in TDD, to decide
when to start DL at eNB side. Since there is a
need for the PA to be operational, we need to
transmit a bit before the DL subframe coming
after an UL subframe. (We transmit zeros.)
We used to use N_TA_offset which may be too much.
Default value is now N_TA_offset/2 and can be
changed in the configuration file, in the RUs
section, like:
RUs = (
{
local_rf = "yes"
nb_tx = 1
nb_rx = 1
att_tx = 0
att_rx = 0;
bands = [7];
max_pdschReferenceSignalPower = -27;
max_rxgain = 105;
eNB_instances = [0];
sf_extension = 312;
}
);
N_TA_offset is 624 (for 30.72MHz). In the example
above, we set sf_extension = 312, which is also
the default.
The value to put in the configuration file is for
30.72MHz. The value is scaled accordingly at runtime
(thus only one value to set for every RB configuration,
25, 50 or 100, leading to less problems when adapting
configuration files).
This option is for experts and should not be changed
randomly.
Florian Kaltenberger